In tawriyah, an expression has an easily suggested near meaning and a more distant intended meaning. Istikhdām uses a word in one sense while a related pronoun or expression engages another sense of that same term.
The vague observation that “one word has two meanings” is not sufficient. Tawriyah depends on the deceptive prominence of the near sense; istikhdām depends on a relationship between the earlier expression and its later reference in a second sense.